Petroleum Drilling Techniques, Issue 4, 2018

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Design and Test of Key Tools in Horizontal Well Toe-End Fracturing


For the coiled tubing undersealing drag technology or bridge plug pumping fracturing technology adopted in the horizontal wells in Daniudi Gas Field and Dongsheng Gas Field, there are many problems in the first stage of toe-end fracturing, such as difficulty in unseating packer, long construction period and high cost of wireline perforation. Based on the field technology, the toe-end sliding sleeve staged fracturing technology was studied, and some key tools, such as toe-end time delay sliding sleeve and seal locking seat, were designed to meet the pressure test requirements of casing string in horizontal wells, and to realize the toe-end non-perforation and full bore fracturing in horizontal wells. Ground test results showed that the key fracturing tools designed in toe-end can realize the functions of locking and sealing in cementing bumping and constant pressure time delay opening of fracturing sliding sleeve. The blasting valve of the toe end time delay sliding sleeve was initiated at the pressure of 82. 0 MPa, the sliding sleeve was successfully opened after 29 minutes' delay, and the bearing pressure of the sliding sleeve reached 105. 0 MPa; the seal locking seat and the matching rubber plug can realize the locking of cementing bumping, and the reverse pressure sealing ability reached 52. 5 MPa. It was verified that the technology has the feasibility of field application. The successful development of the toe-end fracturing tools for horizontal wells could provide technical support for replacing the perforation operation of horizontal wells and reducing the development cost of domestic tight oil and gas reservoirs in the future.